When working with an instrument in an area which cannot be clearly viewed, it may be of importance to record the current position of the instrument and present it in a suitable way. It is known to provide an instrument with electromagnetic position sensors, so-called coil elements. A field generator which is arranged in spatial proximity of the instrument generates an electromagnetic field which induces electric potential in the coil elements of the instrument according to the law of electromagnetic induction (induction law). The level of the induced potential or the electric currents (Ohm's law) in the coil elements may be different according to spatial position and positioning of the sensors at the instrument.
A control unit which is connected with the field generator and the position sensors may subsequently calculate the position of the sensors and thus of the instrument from the different measurement data of the field generator and the position sensors and, for example, present them on a monitor.
Also methods for determining the position of instruments which are based on optical measuring principles of suitable sensors on the instrument are known.
Methods of this sort are applicable for instruments which are rigid and do not deform or warp during use of the instruments. If methods of this sort are applied with instruments which warp during use, the position data cannot be clearly differentiated from possible interfering signals.
From DE 2004 017 834 A1, a catheter device encompassing a catheter to be introduced into a hollow organ, in particular a vessel, with several bending elements which are arranged to be spread along the longitudinal axis of the catheter and which are separately controllable as well as several communicating bending sensors which are arranged to be spread around the longitudinal axis of the catheter is known.
From DE 10 2006 052 886 A1, a system for recording the form of a flexible insertion portion of an endoscope, the system encompassing a position detection system which detects the positions of both ends of a bending section of the insertion portion, a means for determining the bending state of the bending section and a form reproduction processor for reproducing the bending section according to the recorded positions and the bending state is known.